1. Field of the Invention
This invention relates to a mounting structure for an oil pan comprising an outer pan made from a metal and an inner pan made from a synthetic resin and bolted to the underside of an engine.
2. Description of the Related Art
In conventional engine oil pans of the above-described type, an inner pan is bolted to an inner surface of an outer pan (see JP-A-2005-9418, for example) or the inner pan has a flange held between the outer pan and an engine and fastened by bolts (JP-A-2003-222012, for example).
However, the inner pan, which is made from a synthetic resin, has a thermal deformation ratio different from those of the outer pan and engine, both of which are made from respective metals. Accordingly, an internal stress occurs in the inner pan with thermal deformation thereof, resulting in possibility of cracks produced in the inner pan. Furthermore, when held between the outer pan and the engine and fastened by bolts, the flange of the inner pan may creep such that the sealing performance would be reduced in the co-fastened portion.